Shear exfoliation of large-size GO sheets for high-performance films

Graphene-based film with superior mechanical and conductive performance shows potential applications in the fields of environment and energy. The large-scale production of large graphene oxide (GO) sheets is of great significance to improve the properties of macroscopic films. Here, we show an efficient shear exfoliation method for producing GO with large size and high yield. The size control is based on a size-dependent shear exfoliation pattern, in which the shear rate (γ) required for exfoliation increases with initial size of graphite oxide flakes (L0) as power law. In this regard, the production of GO with lateral size of 14 μm and relative single-layer fraction of 80% is realized by optimizing γ and L0. Due to the more compact and oriented structure, the GO film prepared with large GO sheets (~ 14 μm) exhibits superior tensile strength (~ 168.2 MPa), Young’s modulus (~ 8.2 GPa), and electrical conductivity (~ 231.2 S/cm) after HI reduction, which has been increased by 38.8%, 70.8%, and 46.8% than that of GO film prepared with small GO sheets (~ 3.4 μm), respectively. These findings will be of great value in optimizing size and yield of GO sheets and provide useful information to design shear exfoliation process.